Combustible structural composites and methods of forming combustible structural composites

ABSTRACT

Combustible structural composites and methods of forming same are disclosed. In an embodiment, a combustible structural composite includes combustible material comprising a fuel metal and a metal oxide. The fuel metal is present in the combustible material at a weight ratio from 1:9 to 1:1 of the fuel metal to the metal oxide. The fuel metal and the metal oxide are capable of exothermically reacting upon application of energy at or above a threshold value to support self-sustaining combustion of the combustible material within the composite. Structural-reinforcing fibers are present in the composite at a weight ratio from 1:20 to 10:1 of the structural-reinforcing fibers to the combustible material. Other embodiments and aspects are disclosed.

GOVERNMENT RIGHTS

The United States Government has certain rights in this inventionpursuant to Contract No. DE-AC07-05ID14517 between the United StatesDepartment of Energy and Battelle Energy Alliance, LLC.

TECHNICAL FIELD

This invention relates to combustible structural composites and tomethods of forming combustible structural composites.

BACKGROUND OF THE INVENTION

In certain applications, primarily military, vehicles are used to carrya payload to a location of interest. The vehicles might be of land, sea,or air, or some combination thereof. Such might be manned or unmanned.The payload might be personnel and/or equipment. In some instances, thepayload/personnel/cargo is unloaded or used at the location of interestwith the vehicle left behind after serving its primary purpose ofdelivering the payload to such location. An enemy or undesired personsmay thereby have access to or use of the vehicle.

Further in some applications, it might be desirable to transportstructures and/or equipment to a desired location in an assembled orunassembled condition. Upon serving its purposes, the structure(s) orequipment might need to be left behind, and to which an enemy or othersmight undesirably have access. It would be desirable to enable vehicles,structures, and/or equipment to be readily disposed of after such haveserved their useful purpose and/or to preclude such from being accessedby undesirable entities.

While the invention was motivated in addressing the above identifiedissues, it is in no way so limited. The invention is only limited by theaccompanying claims as literally worded, without interpretative or otherlimiting reference to the specification, and in accordance with thedoctrine of equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention are described below withreference to the following accompanying drawings.

FIG. 1 is a diagrammatic top view of a combustible structural compositein accordance with an embodiment of the invention.

FIG. 2 is a cross sectional view taken through line 2-2 in FIG. 1.

FIG. 3 is an alternate embodiment combustible structural composite tothat shown by FIG. 2.

FIG. 4 is an alternate embodiment combustible structural composite tothat shown by FIG. 2.

FIG. 5 is an alternate embodiment combustible structural composite tothat shown by FIG. 2.

FIG. 6 is an alternate embodiment combustible structural composite tothat shown by FIG. 2.

FIG. 7 is an alternate embodiment combustible structural composite tothat shown by FIG. 2.

FIG. 8 is an alternate embodiment combustible structural composite tothat shown by FIG. 2.

FIG. 9 is an alternate embodiment combustible structural composite tothat shown by FIG. 2.

FIG. 10 is an alternate embodiment combustible structural composite tothat shown by FIG. 2.

FIG. 11 is an alternate embodiment combustible structural composite tothat shown by FIG. 2.

FIG. 12 is an alternate embodiment combustible structural composite tothat shown by FIG. 2.

FIG. 13 is an alternate embodiment combustible structural composite tothat shown by FIG. 2.

FIG. 14 is an alternate embodiment combustible structural composite tothat shown by FIG. 2.

FIG. 15 is an alternate embodiment combustible structural composite tothat shown by FIG. 2.

FIG. 16 is an alternate embodiment combustible structural composite tothat shown by FIG. 2.

FIG. 17 is an alternate embodiment combustible structural composite tothat shown by FIG. 2.

FIG. 18 is a diagrammatic top view of another combustible structuralcomposite in accordance with an embodiment of the invention.

FIG. 19 is a cross sectional view taken through line 19-19 in FIG. 18.

FIG. 20 is a diagrammatic top view of another combustible structuralcomposite in accordance with an embodiment of the invention.

FIG. 21 is a cross sectional view taken through line 21-21 in FIG. 20.

FIG. 22 is a diagrammatic isometric view of another combustiblestructural composite in accordance with an embodiment of the invention.

FIG. 23 is a cross sectional view taken through line 23-23 in FIG. 22.

FIG. 24 is a diagrammatic top view of another combustible structuralcomposite in accordance with an embodiment of the invention.

FIG. 25 is a cross sectional view taken through line 25-25 in FIG. 24.

FIG. 26 is an alternate embodiment combustible structural composite tothat shown by FIG. 25.

FIG. 27 is a diagrammatic isometric view of a combustible structuralcomposite during manufacture in accordance with an embodiment of theinvention.

FIG. 28 is a view of the FIG. 27 substrate at a processing stepsubsequent to that shown by FIG. 27.

FIG. 29 is a view of the FIG. 28 substrate at a processing stepsubsequent to that shown by FIG. 28.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

This disclosure of the invention is submitted in furtherance of theconstitutional purposes of the U.S. Patent Laws “to promote the progressof science and useful arts” (Article 1, Section 8).

Aspects of the invention encompass combustible structural composites andmethods of forming combustible structural composites. Such compositesmight be used in any number of existing or yet-to-be developed manners.For example and by way of example only, such might be used as structuralload-bearing components of a vehicle. For example, a combustiblestructural composite might be used as a structural supporting componentof an aircraft wing or fuselage (including the skins thereof), and/orsub-structural components of a wing or fuselage. Alternately by way ofexample, combustible structural composites as described herein might beused as load-bearing structure for land, sea, and/or amphibiousvehicles. Further by way of example only, combustible structuralcomposites as described herein might be utilized as structuralload-bearing components of a building, equipment, orarticles-of-manufacture other than vehicles. Examples include planar andnon-planar sheets which might be used as a surface or internalstructural component of an article of manufacture, of course includingvehicles. Regardless, such load-bearing structural composites will becapable of partial or complete destruction by self-sustaining combustionas described herein. Thereby, a user can selectively choose to destroywholly or partially a structure or piece of equipment by choosing toselectively cause the structural load-bearing composite to burn.

Several embodiments are described below which might be used in thefabrication of structural load-bearing components of vehicles,buildings, other structures and/or equipments, and by way of examplesonly. Referring initially to FIGS. 1 and 2, a combustible structuralcomposite is indicated generally with reference numeral 10. Such is byway of example only, and for convenience of discussion, depicted in theform of an elongated, square cross-sectioned rod. However, any alternateconfiguration or shape is contemplated, and whether existing oryet-to-be developed. For example, such might be of circular crosssection, and/or an expansive thin sheet, and/or other than extendingsubstantially straight linear.

Combustible structural composite 10 is depicted as comprisingcombustible material 12 and structural-reinforcing fibers 14. Thecombustible material comprises a fuel metal and a metal oxide. The fuelmetal might be in an elemental form, including a plurality of differentmetal elements in an elemental form. Alternately by way of example, thefuel metal might be an alloy of elemental metals. Specific examplesinclude aluminum, titanium, zirconium, and magnesium, whether usedeither alone or in any combination, or as an alloy. In one embodiment,the fuel metal comprises aluminum in alloy form, for example magnalium.

A variety of metal oxides might be used. Specific preferred examples areshown in the TABLE below with respect to example fuel metals.

TABLE Fuel Metals Al Ti Zr Mg Metal Oxides Ag B B B B Bi Co Cr Cr Cr CrCu Cu Cu Cu Fe Fe Fe Fe Hg I Mn Mn Mn Mn Mo Nb Ni Pb Pb Pb Pb Pd Si SiSi Si Sn Ta Ti U V W

The fuel metal is present in the combustible material at a weight ratiofrom 1:9 to 1:1 of the fuel metal to the metal oxide. In one preferredembodiment, the fuel metal is present in the combustible material at aweight ratio from 1:4 to 3:7 of the fuel metal to the metal oxide. Thefuel metal and the metal oxide are provided to be capable ofexothermically reacting upon application of energy at or above athreshold value to support self-sustaining combustion of the combustiblematerial within the composite.

A plurality of structural-reinforcing fibers 14 are present in thecomposite at a weight ratio of from 1:20 to 10:1 ofstructural-reinforcing fibers 14 to combustible material 12. In onepreferred embodiment, structural-reinforcing fibers 14 are present inthe composite at a weight ration from 1:2 to 2:1 of thestructural-reinforcing fibers to the combustible material. Thestructural-reinforcing fibers may or may not be combustible or consumedupon self-sustaining combustion of the combustible material within thecomposite, and typically will not be inherently capable of supportingself-sustaining combustion. Fuel metal and metal oxide combustiblematerials typically contain a ceramic phase that makes such too brittlefor use as structural supporting members in place of metals such asaluminum or steel. Such brittle nature makes such combustible materialsunable to carry any meaningful tensile load which is essential in moststructural applications. Addition of reinforcing material such asstructural-reinforcing fibers may result in a composite effectivelycapable of carrying significant structural design loads in addition toproviding increased fracture toughness in comparison to the combustiblematerial alone. Example structural-reinforcing fibers include one ormore of glass fibers (i.e., fiberglass), carbon fibers, and aramidfibers (i.e., Kevlar™). In another example, the fibers may be of acomposition comprising the fuel metal, including of a compositionconsisting essentially of the fuel metal. Regardless, the fibers may beof uniform length and diameter or of variable lengths and/or diameters.Regardless, an example diameter range for fibers 14 is from 4×10⁻⁵ inchto 0.1 inch, and an example length range is from 0.050 inch to 12inches. Other diameters and/or lengths may be used.

Application of energy sufficient to support self-sustaining combustionof the combustible material within the composite might occur by anyexisting or yet-to-be developed manner. Further, selection of the fuelmetal and metal oxide compositions and weight ratio relative to oneanother will impact the threshold energy required to supportself-sustaining combustion. Accordingly, the quantity and manner ofapplying energy may vary upon composition and concentration ofmaterials. For example, compositions may be fabricated such thatself-sustaining combustion can be initiated by a conventional match.Further and by ways of example only, higher or lower energy applicationfor a given material might occur by application of electrical impulse,or microwave or other radiation exposure. Further, some sort of aninitiator might be provided as part of the composite or separately toenable initiation of self-sustaining combustion. For example, a suitableincendiary composition might be provided which can be caused to igniteby a lower energy input (i.e., by a match) to initiate burning thereofat a higher temperature which initiates self-sustaining combustion ofcombustible material 12 at the higher temperature.

As a specific example, a composite comprising combustible material of25.3% by weight aluminum and 74.7% by weight iron oxide will burn onceheated to approximately 800° C. The products are alumina, iron and 4KJ/g of heat. The adiabatic flame temperature for the reaction isgreater than 2000° C.

Dimensions and thickness of structural composite 10 can be selected bythe artisan depending upon resultant strength of the composite and theload carrying configuration desired for a structural supporting memberof which the composite would be a part. Further, additional materialmight be present within or in addition to material 12 and fibers 14.

FIGS. 1 and 2 depict one example embodiment whereinstructural-reinforcing fibers 14 are both received within combustiblematerial 12, and are in direct physical touching contact therewith.Regardless and although not specifically shown in FIGS. 1 and 2,structural reinforcing fibers may extend to one or more outer surfacesof composite 10. FIG. 2 also depicts an embodiment whereinstructural-reinforcing fibers 14 are distributed substantiallyhomogenously within combustible material 12. Alternate embodimentsdepicting other than homogenous fiber distribution are depicted by waysof example only in FIGS. 3, 4, 5 and 6 with respect to combustiblestructural composites 10 a, 10 b, 10 c, and 10 d, respectively. Likenumerals from the first-described embodiment are utilized whereappropriate, with differences being indicated with the suffixes a, b, c,or d.

FIG. 3 depicts an embodiment wherein structural-reinforcing fibers 14are concentrated to one side of combustible structural composite 10 a.FIG. 4 depicts an alternate embodiment wherein structural-reinforcingfibers 14 are concentrated at opposing surfaces of combustiblestructural composite 10 b and away from central portions thereof. FIGS.5 and 6 depict alternate embodiment combustible structural composites 10c and 10 d, respectively, having different spaced concentrated regionsof structural-reinforcing fibers 14. FIGS. 3-6 are examplenon-homogenous fiber distribution embodiments only, and alternateconfigurations are also of course contemplated.

For example, FIG. 7 depicts an alternate example combustible structuralcomposite 10 e wherein the structural-reinforcing fibers are provided inthe composite as a self-supporting sheet. Like numerals from the firstdescribed embodiment have been utilized where appropriate, withdifferences being indicated with the suffix “e” or with differentnumerals. Combustible structural composite 10 e is depicted ascomprising a sheet 16 composed of structural-reinforcing fibers 14. Forpurposes of the continuing discussion, such can be considered as havingopposing side 17, 18 which are both covered by and in physical contactwith combustible material 12. Fibers 14 may or may not be distributedsubstantially homogenously within sheet 16. Further in addition thereto,structural-reinforcing fibers (not shown) might be homogenously orotherwise distributed throughout combustible material 12 on one or bothsides of fiber-comprising sheet 16. An example thickness range for sheet16 is from 0.10 inch to 0.1 inch. Alternate thicknesses might of coursebe used.

FIG. 7 depicts an embodiment wherein sheet 16 is essentially centeredwithin combustible material 12. FIG. 8 depicts an alternate embodimentcombustible structural composite 10 f wherein fiber-comprising sheet 16is provided to be other than centered within combustible material 12.Like numerals from the FIG. 7 embodiment have been utilized, withdifferences being indicated with the suffix “f”.

FIGS. 7 and 8 depict example embodiments wherein a singlefiber-comprising sheet 16 is provided within the respective combustiblestructural composite. FIG. 9 depicts a combustible structural composite10 g wherein multiple sheets 16 have been provided within combustiblematerial 12. Like numerals from the FIGS. 7 and 8 embodiments have beenutilized where appropriate, with differences being indicated with asuffix “g”.

The above FIGS. 7-9 embodiments depict one or morestructural-reinforcing fiber sheets provided in one or more continuoussheets which substantially spans the respective composite. FIG. 10depicts an alternate embodiment combustible structural composite 10 hhaving a plurality of structural-reinforcing fiber sheets 16 h which donot span entirely along composite 10 h. Like numerals from theabove-described FIGS. 7-9 embodiments have been utilized whereappropriate, with differences being indicated with the suffix “h”.

FIG. 11 illustrates another example embodiment combustible structuralcomposite 10 i having a plurality of overlapping structural-reinforcingfiber sheets 16 i. Like numerals from the FIG. 10 embodiment have beenutilized, with differences being indicated with the suffix “i”.

FIG. 12, by way of example only, depicts another embodiment combustiblestructural composite 10 j comprising a plurality of sheets 16 j. Likenumerals from the FIGS. 7-11 embodiment have been utilized whereappropriate, with differences being indicated with the suffix “j”. FIG.12 depicts combustible structural composite 10 as comprising twostructural-reinforcing fiber sheets 16, with combustible material 12being sandwiched therebetween. FIG. 12 also depicts an exampleembodiment wherein combustible material 12 is provided to cover only asingle surface among a plurality of opposing major surfaces of eachstructural-reinforcing fiber sheet 16.

FIG. 13 illustrates yet another alternate example embodiment combustiblestructural composite 10 k. Like numerals from the FIG. 12 embodimenthave been utilized, with differences being indicated with the suffix“k”. FIG. 13 depicts an embodiment employing only a singlestructural-reinforcing fiber sheet 16 k.

Embodiments of the invention also encompass combustible structuralcomposites comprising the above-described combustible material incombination with a structural load-bearing sheet which is bondedthereto, with the structural load-bearing sheet being present in thecomposite at a weight ratio from 1:20 to 10:1 of the structuralload-bearing sheet to the combustible material. For example, FIG. 14depicts such an example combustible structural composite 30. Likenumerals from the above-described embodiments have been utilized whereappropriate, with differences being indicated with different numerals.Combustible structural composite 30 comprises combustible material 12and a structural load-bearing sheet 22 which is bonded thereto.Structural load-bearing sheet 22 might be bonded to or with combustiblematerial 12 with a suitable adhesive (not shown) or by application ofliquid material to sheet 22 followed by solidification thereof intocombustible material 12, for example as described below. In one example,structural load-bearing sheet 22 is composed or comprised of metal, forexample steel, aluminum, or other structural load-bearing metals. In oneexample, structural load-bearing sheet 22 may be of a compositioncomprising the fuel metal, including of a composition consistingessentially of the fuel metal. Fiber-comprising sheets might also beutilized, with any of FIGS. 7-13 depicting example combustiblestructural composites comprising combustible material and at least onestructural load-bearing sheet which may or may not be bonded withcombustible material.

FIG. 14 depicts one embodiment wherein a combustible structuralcomposite 30 comprises a plurality of opposing major surfaces 23 and 24,with structural load-bearing sheet 22 comprising one of such opposingmajor surfaces. FIG. 15 depicts an alternate embodiment combustiblestructural composite 30 a wherein structural load-bearing sheet 22 issubstantially centered between opposing major surfaces 23 a and 24. Likenumerals from the FIG. 14 embodiment have been utilized, withdifferences being indicated with the suffix “a”.

FIG. 16 depicts yet another alternate embodiment combustible structuralcomposite 30 b. Like numerals from the FIGS. 14 and 15 embodiments havebeen utilized, with differences being indicated with the suffix “b”.Combustible structural composite 30 b comprises a plurality of layers 22of structural load-bearing sheets collectively present in the compositeat a weight ratio from 1:20 to 10:1 of the structural load-bearingsheets to the combustible material.

FIG. 17 illustrates yet another embodiment combustible structuralcomposite 30 c. Like numerals from the FIGS. 14-16 embodiments have beenutilized, with differences being indicated with the suffix “c”.Composite 30 c comprises a plurality of layers 12 of combustiblematerial which alternate with at least a layer 22 among the plurality ofstructural load-bearing sheets. Additionally or alternately to thatshown by FIG. 17, combustible material 12 might be provided outwardly(not shown) of outermost sheets/layers 22 to form an opposing majorsurface among the plurality of opposing major surfaces of the composite.

An alternate embodiment combustible structural composite 40 is shown inFIGS. 18 and 19. Like numerals from the first-described embodiments areutilized, with differences being indicated with different numerals.Composite 40 comprises combustible material 12 and metal wire 42 presentin the composite at a weight ratio from 1:20 to 10:1 of the metal wireto the combustible material. A single strand of metal wire might beutilized, with a plurality of strands of metal wire being depicted inthe FIGS. 18 and 19 example. Wire 42 might be comprised of any metal orcombination of metal. In one example, the wire may be of a compositioncomprising the fuel metal, including of a composition consistingessentially of the fuel metal. Regardless, an example wire diameter isfrom 0.0005 inch to 0.100 inch. Alternate diameters might also be used.Individual strands of metal wire 42 might be spaced relative one anotheras shown, or alternately be contacting one another. Further andregardless, where multiple strands of metal wire are used, such might beoriented parallel relative one another, or in non-parallel manners.Further and regardless, such might be oriented to run along thesubstantial length of the composite (as shown), transverse relative tothe length, or otherwise.

FIGS. 20 and 21 depict an alternate embodiment combustible structuralcomposite 40 a. Like numerals from the FIGS. 18 and 19 embodiments havebeen utilized, with differences being indicated with the suffix “a” orwith different numerals. Combustible structural composite 40 a comprisesmetal wire 42 a which is in the form of a sheet 44. In the depictedexample, the sheet comprises a screen mesh. Screen mesh 44 is depictedas being substantially centered between a plurality of opposing majorsurfaces 46 and 47 of composite 40 a, although non-centered orientationsare also of course contemplated. Further, FIGS. 20 and 21 depict asingle screen mesh sheet 44, with multiple of such screen mesh sheetsalso of course being contemplated, and for example oriented as shown inany of the embodiments of FIGS. 8-17, or otherwise.

An alternate embodiment combustible structural composite 40 b is shownin FIGS. 22 and 23. Like numerals from the FIGS. 18-21 embodiments areutilized, with differences being indicated with the suffix “b”.Combustible structural composite 40 b is depicted as being cylindricalor tubular, and comprises metal wire 42 a in the form of a screen meshsheet 44. Combustible material 12 is formed over and through screen meshsheet 44. Metal wire might alternately or additionally be present withina cylindrical combustible structural composite in other than a screenmesh or other sheet, for example and by way of example only in mannersdepicted in the FIGS. 18-21 embodiments.

Another alternate embodiment combustible structural composite 50 isshown in FIGS. 24 and 25. Such comprises a pair of structuralload-bearing sheets 54, 55 having a foam-comprising core 56 receivedtherebetween. Structural load-bearing sheets 54, 55, by way of exampleonly, might be composed of any of the materials and configuration of thesheets described in connection with any of the FIGS. 7-17 embodiments.

Foam-comprising core 56 comprises a plurality of combustible materialmasses 52 received within a foam 58. Composition of combustible materialmasses 52 is the same as that described above for combustible material12. Any suitable or yet-to-be developed foam 58 is usable, withRohacell™ available from Evonik Industries, being but one example.Combustible material masses 52 are depicted as being generally sphericaland centered within foam 58 between pair of structural load-bearingsheets 54, 55. Other shapes and orientations are also of coursecontemplated. Further, combustible structural composite 50 is depictedas having only two structural load-bearing sheets received onouter/external surfaces thereof. Alternately by way of example only,such sheets might be received within foam 58 (less preferred), and/oralternately a plurality of layers of pairs of structural load-bearingsheets and foam-comprising cores might be used.

An example alternate embodiment combustible structural composite 50 a isshown in FIG. 26. Like numerals from the FIGS. 24 and 25 embodiment havebeen used, with differences being indicated with the suffix “a” or withdifferent numerals. Here, foam-comprising core 56 a can be considered ascomprising opposing major surfaces 51 and 53 each of which is receivedproximate different of the respective structural load-bearing sheets 54,55 of the pair. Combustible material masses 52 are shown to extendcompletely through foam 58 from one of opposing major surfaces 51, 53 tothe other. In one example and preferred embodiment, masses 52 arecylindrical.

The above example combustible structural composites might bemanufactured by any existing or yet-to-be developed manner, and in anyshapes or configurations. In one example, a tape casting-like processmight be utilized. For example, a suitable mixing container is usedwithin which suitable binders and solvents are mixed. Powders of thefuel metal and the metal oxide are added thereto. Further, anotheroxidizer for the binder might also be added, such as potassiumperchlorate. In one embodiment where structural-reinforcing fibers arepresent throughout the composite, such fibers may also be added, and themixture stirred until homogeneity is obtained.

A suitable surface which is ideally chemically inert to the solvent, forexample Mylar™, is provided. A suitable mold shape may be provided overthe surface, and the mixture poured or otherwise spread over suchsurface within the mold or in the absence of a mold. The resultantcomposition is then allowed to dry either at room temperature or atelevated temperature to evaporate the solvent, with the binder orbinders holding the resultant composite together. The process may ofcourse be repeated to form multiple layers and a larger composite. Thebinder will likely not be combustible, and thereby may compromise theexothermic output of the combustible material wherein some of the energystored by the combustible material will be utilized to decompose thebinder upon burning the combustible material. Regardless, compositescontaining binders may be subjected to further treatments, such as hotpressing to increase their density and toughness. In such event, much ofthe binder might be eliminated by exposure to the high temperaturesassociated with such treatments.

If using sheets of structural-reinforcing fibers, metal or othercomposition, or metal wire, such might be laid over a chemically inertsurface with or without a mold, and the above liquid composition spreadthereover. Upon cure, the process could be repeated with the solventcomposition bearing the combustible material with or without provisionof additional structural-reinforcing sheets and/or metal wire.

An alternate example process includes hot-pressing which may use nobinder. For example, structural-reinforcing fibers in combination withcombustible material as described above may be placed into a graphitemold. Such mixture is then ideally brought to near the meltingtemperature of the fuel metal, and placed under high pressure. Ideally,temperature is maintained below the melting temperature of the fuelmetal but at or above its plastic transition temperature. Thecombustible material plastically flows together and around thereinforcing material and densifies. Pressing would occur, for example at10,000 psi for 15 minutes, whereupon a solidified composite of a desiredshape is formed. Subsequent machining thereof may or may not beconducted.

Another example technique is a thermal spray coating process to depositthe combustible material onto structural-reinforcing material with orwithout using a mold. Such an example process includes introducing fuelmetal and metal oxide in combination or separately into a hot gas jetstream that is generated by either electric arc discharge (plasma) oroxygen-fuel combustion. The particles are heated and accelerated by thegas jet to be deposited onto a structural-reinforcing substrate (i.e., afibrous or metal sheet, or metal wire) to form a coating thereon. Aniterative approach is ideally implemented with additional combustiblematerial being deposited. Further, additional reinforcing material maybe laid down at desired thickness intervals.

With such a thermal spray process, the powder particles essentially meltin-flight and impact upon the surface onto which such are sprayed. Suchforms a strong bond with one another and the reinforcing material. Uponcompletion, the composite may or may not be densified to reduce voidvolume that may occur during the thermal spray process. Densification,by way of example only, might be conducted by hot press and/or hotisostatic press.

An aspect of the invention encompasses methods of forming a combustiblestructural composite. In one embodiment, a liquid mixture is sprayedonto and through a screen mesh. The screen mesh may comprise metaland/or other material. The screen mesh may be planar, cylindrical, or ofany other desired shape or configuration. The screen mesh may rest upona substrate or be elevated above a substrate or other surface during thespraying.

The sprayed liquid is solidified into combustible material which coversa plurality of opposing surfaces of the screen mesh, with thecombustible material comprising a fuel metal and a metal oxide asdescribed in the above embodiments with respect to material 12. In oneexample preferred embodiment, the liquid mixture is molten and at atemperature above that of the screen mesh during the spraying. In oneexample preferred embodiment where the screen mesh comprises a cylinder,the screen mesh cylinder is rotated about its longitudinal axis duringthe spraying, with the solidifying forming the combustible material toline an internal surface and an external surface of the cylinder. Forexample, the combustible structural composite 40 b of FIGS. 22 and 23might be formed in such a manner.

In one specific example, a tubular combustible structural composite wasformed using a plasma spray process by first forming an aluminum screensubstrate into a desired tubular shape. For example, an aluminum wiremesh was formed into a tubular structure of 12.7 mm in diameter by 125mm long. The tube was rotated while a plasma torch was translated acrossthe tube longitudinally while spraying a mixture of molten fuel metaland metal oxide with the torch. The exit of the torch was positionedbetween 25 mm and 200 mm from the rotating tubular structure. Theprocess was repeated multiple times until a desired coating was providedinternally and externally on the wire mesh. The process further may berepeated to provide a thicker external coating on the tubular structurethan internally within the tubular structure upon complete covering ofthe openings in the wire mesh.

The plasma torch was operated using 10 to 60 standard liters per minute(slm) of argon and from 0 to 20 slm of helium. Torch current wasadjusted between 400 amps and 1,000 amps. The result was a free-standingtubular structure approximately 13.7 mm in diameter with an internal andexternal wall thickness greater than 1 mm. Not including the wire meshsubstrate, the structure was composed of approximately 32% by weightfuel metal, 65% by weight combustible material, and 3% porosity.

The combustible structural composites described above in connection withFIGS. 24 and 25 might also be manufactured in accordance with anyexisting or yet-to-be developed methods. For example and by way ofexample only, a structural foam core comprising combustible materialmasses could be sprayed or otherwise provided in liquid form onto astructural load-bearing sheet, and then solidified into a solid foam.Another structural load-bearing sheet could be bonded thereto orotherwise connected therewith. Further by way of example only, a liquidfoam comprising combustible material masses therein could be injectedbetween a pair of structural load-bearing sheets and solidified to bondwith each of the load-bearing sheets during a solidification process.

An aspect of the invention also encompasses forming a combustiblestructural composite, for example as described in connection with FIGS.27-29 in forming the example combustible structural composite 50 a ofFIG. 26. Like numerals from FIG. 26 have been used, with differencesbeing indicated with different numerals. Referring to FIG. 27, afoam-comprising sheet 58 has been bonded to or with a structuralload-bearing sheet 55. A plurality of holes 70 has been formed to extendinto foam-comprising sheet 58. In one example embodiment and as shown,holes 70 have been formed to extend transversally and completely throughfoam-comprising sheet 58 from major opposing surface 51 to the othermajor opposing surface 53.

Regardless and referring to FIG. 28, a combustible material mass 52 hasbeen inserted into at least a hole among the plurality of holes 70 inthe foam-comprising sheet 58. A combustible material mass 52 might beloosely or tightly received within a hole 70, and may or may not beglued there-within with a suitable adhesive.

Referring to FIG. 29, structural load-bearing sheet 54 has been bondedto the foam-comprising sheet 58 having combustible material masses 52(not viewable in FIG. 19) received there within.

In compliance with the statute, the invention has been described inlanguage more or less specific as to structural and methodical features.It is to be understood, however, that the invention is not limited tothe specific features shown and described, since the means hereindisclosed comprise preferred forms of putting the invention into effect.The invention is, therefore, claimed in any of its forms ormodifications within the proper scope of the appended claimsappropriately interpreted in accordance with the doctrine ofequivalents.

1. A combustible structural composite, comprising: a combustiblematerial comprising a fuel metal and a metal oxide, the fuel metal beingpresent in the combustible material at a weight ratio from 1:9 to 1:1 ofthe fuel metal to the metal oxide, the fuel metal and the metal oxidebeing capable of exothermically reacting upon application of energy ator above a threshold value to support self-sustaining combustion of thecombustible material within the composite; and a plurality ofstructural-reinforcing fibers present in the composite at a weight ratiofrom 1:20 to 10:1 of the structural-reinforcing fibers to thecombustible material form.
 2. The composite of claim 1 wherein the fuelmetal is in an elemental
 3. The composite of claim 1 wherein the fuelmetal is an alloy of elemental metals.
 4. The composite of claim 1wherein the fuel metal comprises at least one selected from the groupconsisting of aluminum, titanium, zirconium, and magnesium.
 5. Thecomposite of claim 1 wherein the fuel metal comprises aluminum in alloyform.
 6. The composite of claim 5 wherein the fuel metal comprisesmagnalium.
 7. The composite of claim 1 wherein the metal oxide comprisesan oxide of at least a metal selected from the group consisting of iron,copper, boron, chromium, manganese, lead, and silicon.
 8. The compositeof claim 1 wherein the fuel metal is present in the combustible materialat a weight ratio from 1:4 to 3:7 of the fuel metal to the metal oxide.9. The composite of claim 1 wherein the structural-reinforcing fibersare present in the composite at a weight ratio from 1:2 to 2:1 of thestructural-reinforcing fibers to the combustible material.
 10. Thecomposite of claim 1 wherein the structural-reinforcing fibers compriseat least one selected from the group consisting of glass fibers, carbonfibers, and aramid fibers.
 11. The composite of claim 1 wherein thestructural-reinforcing fibers contact the combustible material.
 12. Thecomposite of claim 11 wherein the structural-reinforcing fibers arereceived within the combustible material.
 13. The composite of claim 12wherein the structural-reinforcing fibers are distributed homogenouslywithin the combustible material.
 14. The composite of claim 1 whereinthe structural-reinforcing fibers are provided in the composite as asheet.
 15. The composite of claim 14 wherein the structural-reinforcingfibers contact the combustible material.
 16. The composite of claim 15wherein the sheet is covered on opposing sides by the combustiblematerial.
 17. The composite of claim 14 wherein the sheet comprises aplurality of opposing major surfaces, the combustible material beingprovided to cover only a single surface among the opposing majorsurfaces.
 18. The composite of claim 14 wherein thestructural-reinforcing fibers are provided in the composite as aplurality of sheets.
 19. A combustible structural composite, comprising:a combustible material comprising a fuel metal and a metal oxide, thefuel metal being present in the combustible material at a weight ratiofrom 1:9 to 1:1 of the fuel metal to the metal oxide, the fuel metal andthe metal oxide being capable of exothermically reacting uponapplication of energy at or above a threshold value to supportself-sustaining combustion of the combustible material within thecomposite; and a metal wire present in the composite at a weight ratiofrom 1:20 to 10:1 of the metal wire to the combustible material.
 20. Thecomposite of claim 19 wherein the metal wire comprises a sheet.
 21. Thecomposite of claim 20 wherein the metal wire comprises a screen mesh.22. The composite of claim 20 wherein the composite comprises aplurality of opposing major surfaces, the sheet being substantiallycentered between the opposing major surfaces.
 23. The composite of claim19 wherein the composite is cylindrical.
 24. The composite of claim 19wherein the metal wire is of a composition comprising the fuel metal.25. The composite of claim 19 wherein the metal wire is of a compositionconsisting essentially of the fuel metal.
 26. A combustible structuralcomposite, comprising: a combustible material comprising a fuel metaland a metal oxide, the fuel metal being present in the combustiblematerial at a weight ratio from 1:9 to 1:1 of the fuel metal to themetal oxide, the fuel metal and the metal oxide being capable ofexothermically reacting upon application of energy at or above athreshold value to support self-sustaining combustion of the combustiblematerial within the composite; and a structural load-bearing sheetbonded to the combustible material, the structural load-bearing sheetbeing present in the composite at a weight ratio from 1:20 to 10:1 ofthe structural load-bearing sheet to the combustible material.
 27. Thecomposite of claim 26 comprising a plurality of layers of structuralload-bearing sheets collectively present in the composite at a weightratio from 1:20 to 10:1 of the structural load-bearing sheets to thecombustible material.
 28. The composite of claim 27 comprising aplurality of layers of the combustible material being alternatinglydisposed with at least a layer of the plurality of structuralload-bearing sheets.
 29. The composite of claim 26 wherein thestructural load-bearing sheet comprises metal.
 30. The composite ofclaim 26 wherein the composite comprises a plurality of opposing majorsurfaces, the structural load-bearing sheet being centered between theplurality of opposing major surfaces.
 31. The composite of claim 26wherein the composite comprises a plurality of opposing major surfaces,the structural load-bearing sheet comprising an opposing major surfaceamong the plurality of opposing major surfaces.
 32. A combustiblestructural composite, comprising: a pair of structural load-bearingsheets having a foam-comprising core received therebetween; and thefoam-comprising core comprising a plurality of combustible materialmasses received within a foam, the combustible material massescomprising a fuel metal and a metal oxide, the fuel metal being presentin the combustible material at a weight ratio from 1:9 to 1:1 of thefuel metal to the metal oxide, the fuel metal and the metal oxide beingcapable of exothermically reacting upon application of energy at orabove a threshold value to support self-sustaining combustion of thecombustible material within the composite.
 33. The composite of claim 32wherein the masses are spherical.
 34. The composite of claim 32 whereinthe core comprises opposing major surfaces each of which is receivedproximate different of the respective structural load-bearing sheets ofthe pair, the combustible material masses extending completely throughthe foam from one of the opposing major surfaces to the other.
 35. Thecomposite of claim 34 wherein the masses are cylindrical.
 36. A methodof forming a combustible structural composite, comprising: forming aplurality of holes extending into a foam-comprising sheet; inserting acombustible material mass into a hole among the plurality of holes inthe foam-comprising sheet, the combustible material mass comprising afuel metal and a metal oxide, the fuel metal being present in thecombustible material at a weight ratio from 1:9 to 1:1 of the fuel metalto the metal oxide, the fuel metal and the metal oxide being capable ofexothermically reacting upon application of energy at or above athreshold value to support self-sustaining combustion of the combustiblematerial within the composite; and disposing the foam-comprising sheetcontaining the combustible material mass between a pair of structuralload-bearing sheets.
 37. The method of claim 36 comprising forming theplurality of holes to extend transversally and completely through thefoam-comprising sheet, the combustible material mass being disposedcompletely through the foam-comprising sheet from a first major opposingsurface of the foam-comprising sheet to a second major opposing surfaceof the foam-comprising sheet.
 38. The method of claim 36 wherein thecombustible material mass is placed within the hole and glued to thefoam-comprising sheet.
 39. A method of forming a combustible structuralcomposite, comprising: spraying a liquid mixture onto and through ascreen mesh; and solidifying the sprayed liquid mixture into acombustible material covering a plurality of opposing surfaces of thescreen mesh, the combustible material comprising a fuel metal and ametal oxide, the fuel metal being present in the combustible material ata weight ratio from 1:9 to 1:1 of the fuel metal to the metal oxide, thefuel metal and the metal oxide being capable of exothermically reactingupon application of energy at or above a threshold value to supportself-sustaining combustion of the combustible material within thecomposite.
 40. The method of claim 39 wherein the screen mesh comprisesa metal.
 41. The method of claim 39 wherein the liquid mixture is moltenand at a temperature above that of the screen mesh during the spraying.42. The method of claim 39 wherein the screen mesh is planar.
 43. Themethod of claim 39 wherein the screen mesh is cylindrical.
 44. Themethod of claim 39 wherein the screen mesh comprises a cylinder, thecylinder being rotated about a longitudinal axis of the cylinder duringspraying such that the combustible material lines an internal surfaceand an external surface of the cylinder.